The gray wolf has been protected for about 40 years, but lost the protected or endangered status in the upper-Midwest last January. Congress is now trying to lift the protections for the animal in rest of the lower 48 states, saying that uncontrolled population growth has affected livestock on farms and imposed “tragic damages” to moose, elk and bighorn sheep in the wild.

There are about 5,000 gray wolves in the continental U.S., with a vibrant population of about 11,000 in Alaska that goes unprotected, according to the U.S. Fish and Wildlife Service. The animals were formerly one of the most common in the nation until mass hunts nearly left them extinct.

A handful of animal welfare groups, led by the Humane Society of the United States,issued a lawsuit last month to restore the gray wolf’s protections in the Midwest, according to The Associated Press.

Michigan, Minnesota and Wisconsin are the largest home to the gray wolf outside of Alaska, with populations that totaled an estimated 4,400 before their protections lapsed. Smaller populations can be found in in Idaho, Montana, Oregon, Wyoming, Washington, New Mexico and Arizona.

Animal welfare groups claim that since the protections ended last year, hunters have killed hundreds of wolves in those states.